The incidence of skin tumors has been increasing in the recent years. The average annual incidence of BCC in the general population of the United States in 191 new lesions per 100,000 white persons. The major environmental factor associated with increased incidence of BCC is Uv exposure. The recent years of depletion of the atmosphere's ozone layer increased the does of UV radiation. The tumor suppressor genes, p53, PTCH and PTEN/MMAC1/TEP1 have been demonstrated to be implicated in the carcinogenesis of BCC. A subgroup Of BCC samples showed the UV specific mutations, C->T transitional change or CC->TT double base change, in the three tumor suppressor genes. These specific mutation patterns established a link between UV exposure and the development of BCC. In this proposal, we will screen a total of 100 primary BCC samples for the mutations in the three tumor suppressor genes, and we will correlate the specific mutation in one, two or three tumor suppressor genes with the specific risk factors.